OFFSET
1,2
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
Fibbinary number 21 is a term because sigma(21) = 32 is also a Fibbinary number.
MAPLE
fibbinary:= n -> Bits:-And(n, 2*n)=0:
select(t -> fibbinary(t) and fibbinary(numtheory:-sigma(t)), [seq(i, i=1..2000)]); # Robert Israel, Apr 02 2018
MATHEMATICA
FibbinaryQ[n_] := BitAnd[n, 2 n] == 0; Select[Range[2000] - 1,
FibbinaryQ[#] && FibbinaryQ[DivisorSigma[1, #]] &] (* Ray Chandler, Jan 08 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Altug Alkan, Jan 06 2017
EXTENSIONS
Terms confirmed by Ray Chandler, Jan 08 2017
STATUS
approved